1. Field of the Invention
The present invention relates to a radiation detecting apparatus having a radiation detector for detecting radiation which has passed through a subject and a contactless power receiver, a radiographic image capturing system having a contactless power feeder for contactlessly supplying electric power to such a radiation detecting apparatus, and a radiographic image capturing method.
2. Description of the Related Art
In the medical field, there have widely been used radiographic image capturing apparatus, which apply radiation to a subject and guide the radiation that has passed through the subject to a radiation conversion panel, which captures a radiographic image from the radiation. Known forms of the radiation conversion panel include a conventional radiation film for recording a radiographic image by way of exposure, and a stimulable phosphor panel for storing radiation energy representing a radiographic image in a phosphor and reproducing the radiographic image as stimulated light by applying stimulating light to the phosphor. The radiation film with the recorded radiographic image is supplied to a developing device to develop the radiographic image, or the stimulable phosphor panel is supplied to a reading device to read the radiographic image as a visible image.
In the operating room or the like, it is necessary to read and display a recorded radiographic image immediately from a radiation conversion panel after the radiographic image has been captured for the purpose of quickly and appropriately treating the patient. Patients such as infants, children, aged people, or those who cannot stand themselves for a long time due to illness or injuries also need to be imaged quickly. As a radiation conversion panel which meets such a requirement, there has been developed a direct-conversion-type radiation detector for converting radiation directly into electric signals or an indirect-conversion-type radiation detector for converting radiation into visible light with a scintillator and then converting the visible light into electric signals with a solid-state detector to read a detected radiographic image.
Japanese Laid-Open Patent Publication No. 2008-170315 discloses a radiation detecting apparatus (electronic cassette) having a function to transmit radiographic image information produced by a radiation detector to an image processor or the like via a wireless transmission system. The electronic cassette incorporates a battery therein. For charging the battery, the electronic cassette is mounted on a separate cradle having a contactless battery charger. The battery is wirelessly charged by the contactless battery charger while the electronic cassette is being mounted on the cradle.
According to the radiation detecting apparatus disclosed in Japanese Laid-Open Patent Publication No. 2008-170315, when the remaining power level of the battery of an electronic cassette in current use runs low after the radiation detecting apparatus has been used to capture a plurality of radiographic images of many patients or a patient during a surgical operation on the patient or when the remaining power level of the battery runs low right after charging because the battery is end-of-life, it is necessary to remove the electronic cassette from under the patient, bring the electronic cassette to the cradle, and charge the battery in the electronic cassette that is mounted on the cradle. However, such a charging process is troublesome and possibly tends to make the surgical operation time-consuming and be burdensome to the patient.
In order to solve the above problem, contactless (wireless) power feeding is effective, in which a battery can be charged on the spot without moving to the cradle. However, in this case, electromagnetic wave generated in the contactless feeding may affect minute analog signals of a radiation detector adversely. If a radiographic image is captured while the battery of the electronic cassette is contactlessly charged, noise caused by magnetic fluxes used for the contactless power feeding is liable to adversely affect the radiographic image information. As a result, it is highly possible for the radiation detecting apparatus to fail to acquire high-quality radiographic images. At worst, noise-induced artifact and adverse effect on the radiographic image may result in erroneous diagnosis and erroneous decision during an operation.